@Liam, well we made some some small modifications in the form-cshtml and then we're using a custom Workflow that internally use lots of stuff from Umbraco's build in Workflow.

In the forms cshtml:

We add two fields

• A input-text that we move out of screen with CSS (like position: absolute; top:1500px; or something) This is expected to always be empty since no user would be able to fill it out. Good practice to not name it name, zip, city or something since autofill in browser might fill this out.
• A input-hidden with a timestamp of when the form was loaded.

The Workflow:

 public class SendEmailEnhancedWorkflow : WorkflowType
 {

    private readonly IHttpContextAccessor _httpContextAccessor;
    private readonly IFieldTypeStorage _fieldTypeStorage;

    [Umbraco.Forms.Core.Attributes.Setting("",
        Name = "Receiver Email(s)",
        Description = "Enter receiver email(s), separate with semicolon if more than one.",
        Alias = "receiverEmails",
        PreValues = "",
        View = "TextArea")]
    public string ReceiverEmails { get; set; }

    [Umbraco.Forms.Core.Attributes.Setting("",
        Name = "Subject",
        Description = "Enter a subject for the e-mail. If empty a generic subject will be used.",
        Alias = "subject",
        PreValues = "",
        View = "TextString")]
    public string Subject { get; set; }

    public SendEmailEnhancedWorkflow(
        IHttpContextAccessor httpContextAccessor,
        IFieldTypeStorage fieldTypeStorage
        )
    {

        _httpContextAccessor = httpContextAccessor;
        _fieldTypeStorage = fieldTypeStorage;


        this.Id = new Guid("F3D257D0-E203-452B-BA83-D5A6E7356AF5");
        this.Name = "Send Email (Enhanced)";
        this.Description = "Sends email with enhanced details in the body (ie Page Url).";
        this.Icon = "icon-message";

    }

    public override WorkflowExecutionStatus Execute(Record record, RecordEventArgs e)
    {
        // Checks both a "meta field" (a text box moved out of screen with css) and the timing between form load and posting.
        // If honeypot if not passed we return completed without sending a email. The PassedHoneyPot-method also removes
        // the entry from the database
        if (!UmbracoFormsWorkflowHelper.PassedHoneyPot(_httpContextAccessor, record))
            return WorkflowExecutionStatus.Completed;

        var emailSubject = "From website";
        if (!string.IsNullOrEmpty(this.Subject))
            emailSubject = this.Subject;

        UmbracoFormsWorkflowHelper.SendEmail(this.ReceiverEmails, emailSubject, record, _fieldTypeStorage, _httpContextAccessor);

        return WorkflowExecutionStatus.Completed;
    }

    public override List<Exception> ValidateSettings()
    {
        if(string.IsNullOrEmpty(this.ReceiverEmails))
            return new List<Exception>(){new ArgumentException("Receiver Email's can't be empty. Add at least one receiver.")};

        return UmbracoFormsWorkflowHelper.ParseExceptionsFromDelimitedEmailString(this.ReceiverEmails);
    }

}

Parts of the the helper:

namespace Site.Web.Forms.Workflow
{
  public class UmbracoFormsWorkflowHelper
  {

    public static bool PassedHoneyPot(IHttpContextAccessor httpContextAccessor, Record record)
    {
        // Perform checks and make sure that the meta input is empty and that X time has passed between the form was loaded and posted.

        if (didPass)
        {
            return true;
        }
        else
        {
            // Log rejected form post
            StringBuilder sb = new StringBuilder();
            foreach (var field in record.RecordFields)
            {
                sb.Append($"{field.Value.Alias}: {field.Value.ValuesAsString()}\n");
            }
            var postedFormValues = sb.ToString();

            DependencyResolver.Current.GetService<ILoggerStructured>().Warn<UmbracoFormsWorkflowHelper>("Form submission was caught by HoneyPot: {honeyPotCaptureType}", honeyPotCaptureType, postedFormValues);


            Task.Run(() => DeleteRecordWithDelay(record.UniqueId.ToString(),record.Form.ToString()));

            return false;
        }

    }

    public static async Task DeleteRecordWithDelay(string recordId,string formId)
    {

        await Task.Delay(2500);

        try
        {
            IRecordService recordService = DependencyResolver.Current.GetService<IRecordService>();
            IRecordStorage recordStorage = DependencyResolver.Current.GetService<IRecordStorage>();
            IFormService formService = DependencyResolver.Current.GetService<IFormService>();

            var form = formService.GetForm(Guid.Parse(formId));
            var record = recordStorage.GetRecordByUniqueId(Guid.Parse(recordId), form);

            recordService.Delete(record, form);
        }
        catch (Exception e)
        {

            var exception = e.Message;
            throw;
        }

    }
}

}

Hope these pointers was helpful =D