I've just come back from Seething (
Seething Airfield - Flying Club) - lovely place, 800m tarmac, £10 donation for landing, reasonable fuel price (£141 for 70l) and it certainly extended my experience (now 57H C150 PPL) getting there from Blackpool (very many CTAs and MATZs on/nearby the route). Looks a lot more convenient for you - think you will just need to talk to the Yanks (Mildenhall / Lakenheath) on the way over, and do check there will be someone in before setting off, though you should have plenty of fuel to get back if it's locked up!