I would like to keep this as distinct as possible from the rented property, but I’ve had to set up a new HMRC account in order to add VAT registration - to which I’ve entered a sole trader trading name (which applies the second business arrangement, not the rental property).
As a sole trader, is there a way to keep the two endeavours separate in terms of tax/accounting, or do I include the rental property income with the second business income under the new trading name?
Ref vat registration it's either you as the individual on your own or something else - note the trading name is irrelevant , when you signup as just you it should be clear that its just you as an individual and i would expect the registration would be linked against your UTR you use for self assessment.
Note anything you do as an individual will fall within this same vat registration as long as its only you legally speaking.
So presuming you have property rental income and the property is solely in your name that will be part of the same vat registration and the exempt residential letting income (presuming thats what it is) will need to be delared as approrpiate. Technically there could be partial exemption calculation sneeded - its reasonably likely here though that this situation could be beneficial if you have sufficient non exempt income from your new trade as its likely that you can claim back input vat on rental expenses under the deminimis rules.
There is no way to avoid everything being classed as one if both endevours are solely in your name - if property was in joint names that would be compeltely separate - your easiest other option if you want to keep separate is to set up the vat registered trade as a limited company - a limited company is a separte entity in its own rights even if you are sole shareholder - that may not be an option though if you specifically wanted to be sole trader and not limited company.