As has been said, I think the only "3-phase bits and pieces" are the 3-phase cutout and meter - which, as both you and I have suggested, would probably be best retained. Most of the bulky stuff there relates to the storage heaters (now going or gone), so that can be removed, and all the various CUs etc. will probably be replaced by a single one - at which point the OP should have a simple and tidy installation (and few, if any Henley blocks!).I'd not worry about the 3-Phase bit and peices unless they really are in your way. The meter is a mdern (read industrial 'smart') 3Phase one. Doesn't matter if one, two or all 3 phases are consuming energy it has only one output so will serve as a domestic one also.
Very much so - much as I said above ("if it were me..."). I have a 3-phase installation and, although I'm using all three phases, I could manage quite happily with just a single-phase one supply - but there's no way that I would dream of 'getting rid of' the 3-phase supply.Any property with 3phase and a 3P meter installed is worth more. Please don't ask the supplier to remove it 'cause if you or your successor in the property want 3 phase for their use it is so expensive to have it installed and the reasoning to have installed so converluted and difficult.
Kind Regards, John