gpn01,
The most likely traffic to be in a cloud in Open FIR is going to be another glider (or several) on 130.4.
I'm very surprised by that comment; where did you glean that information because it is surely incorrect? From practical experience I disagree most strongly. I have flown TCAS equipped rotary aircraft in "open FIR" for a living for ten years now (twenty years before without). One thing TCAS has taught me is to always use an appropriate radar service where available. The number of transponder equipped aircraft operating in Class G in IMC is increasing all the time, much of it rotary wing. On an average IFR / IMC flight from the south of England to the Leeds area I nearly always encounter a number of other aircraft carrying out IMC transits, either informed by ATC or via TCAS, or both.
If you fly in IMC over Bedford you really should speak to Cranfield Approach on 122.850 who do not have radar, but they do give a very useful FIS and will obviously pass details of aircraft in their instrument pattern, which is sometimes
very busy). Bedford is only 2 miles east of the CIT NDB and therefore any glider circling in cloud is dangerously close to the instrument letdown for their main runway 21 and aircraft holding at the beacon at varying levels, including jet traffic. Bedford is also directly on a track commonly used by IFR helicopters coming through the Luton CTR via their overhead and routing just west of the Bedford Danger Area 206 before continuing north or northwest bound via LIC or east of the EME.
A call to Luton would at least give them the chance to inform other aircraft speaking to them about your presence, even if you didn't remain on frequency (a call departing the area would be appreciated too). North of Bedford a call to Cottesmore 130.20 would allow them to do the same for aircraft participating in their LARS service.