Can you recommend a good transport cafe off the M1?

I'm traveling from West Yorkshire to Billericay on Saturday morning, and would like to arrange to meet at a Transport Cafe some friends traveling from West Midlands. I would like to suggest that we meet at a transport cafe for breakfast and then can convoy from there. Ideally, would like to suggest a transport cafe adjacent or very near to the motorway between Northampton and the M25. Anyone point me in the right direction and what the breakfast is like (would like anything remotely like a gut buster!!!) THANKS