Not looking at all good for World Stock Indices. Cash flowing out to the USD. GBP denominated Global/US funds have done relatively well by getting out of the GBPUSD downtrend but I think the safer option now is to buy USD through an ETF.
IPM Pensions will act as Trustee to your SIPP. They say they will entertain numerous trading platforms (as long as the broker will trade SIPP funds).
They specifically told me they would let me operate a CFD SIPP with the GFT platform (GFT are ok with this too). IPM's charge for this is not...