Nutmeg

what says rof?

i have a fairly modest amount in a sipp in some (mostly vanguard) funds. I can’t be arsed really to keep on top of it and don’t make massive contributions. 

Any thoughts...?

Assuming that you can't get the SIPP wrapper directly with Vanguard (I know they offer ISAs), then Nutmeg is fine. I've used them for a while and don't have anything particularly noteworthy to say about them other than the reporting is poor (all returns are reported as absolute, with no option for IRR, etc.).

If you can, sticking with Vanguard will save you the management fee you'll pay on top of the cost of the funds, I believe.