beerdrinker:
I call London Info with an ETA of the FIR boundary at position SITET. What do I ask for? BASIC?
I then cross the coast and change to Farnborough. Again what do I ask for? Not BASIC surely? DECONFLICTION?
You know it's really not that difficult. If you previously asked for RIS and FIS then just ask for Traffic Service and Basic Service respectively.
As to your specific scenario:
1. London Info has no access to radar so can only offer you a Basic Service irrespective of what you may ask them for.
2. You can ask Farborough LARS for whatever service is appropriate to your needs. If you're happy to rely on see and avoid, ask for a BS. If you'd like some idea of what other traffic is around, but don't want to be vectored all over the shop to avoid it, ask for a TS. If you want some assurance that nothing will ever come closer to you than 3nm/1000ft, and you're either not bothered about being vectored into IMC or the weather's wall-to-wall VMC, then ask for a DS.
For most pilots the new services are virtually identical to the existing ones.
NS
PS: Flying at the weekend, on VFR flights o/CAS with a discrete squawk, received very nice radar-based traffic info (of the "traffic in your vicinity" variety) despite being on a FIS. I don't believe that'll change after 12 March.