The V22 Osprey is not in service with the RAF, though it is being considered for certain Special Forces roles. However, there is a USAF V22 Squadron based at RAF Mildenhall, Suffolk. The 7th Special Ops Sqn of the 352nd Special Ops Wing operates both the V22 and the MC130J Cambat Talon in a number of special forces roles. That may well include POTUS security roles when he's in theatre.
'Marine 1' is any one of a number of Sikorsky S61 helicopters maintained at Andrews AFB for the transport of POTUS. One will be brought to Mildenhall by a C5 or possibly a C17 in the days before the visit if it's considered appropriate for Trump to travel by that means (and I suspect it will). The V22s and other aircraft (including F15E Strike Eagles from RAF Lakenheath) will provide an airborne protective escort.