IME, it really depends on what your company is willing to pay. 8 months doesn't seem long enough to require a trip back 'home' but hey, if your company wants to pay, great!
My DH's contract gives us £12k to move back to the States (or elsewhere) but that move would have to be approved/justified. But that's a figure at least that might help.
We were compensated for our move including shipping our house, flights, necessary purchases (all new appliances), hired furniture/linens, mattresses, etc. We were not compensated for things like council tax, tv license, buying a new car, or the cost of selling our US home and vehicles. We do not receive a housing stipend, it just comes from my DH's salary which he thankfully got a great one in £.
If I can encourage anything, it would be for you to be paid in £, not USD. The exchange rate is a killer, and most likely the cost of living will be higher for you compared with the US.
We also negotiated a line item to pay for a UK tax consultant. And one trip per calendar year (to US including Hawaii) but we haven't used that so we just roll the money into the next year.
The other thing I find helpful is some kind of clause in the contract where you will be given say, two months notice, if the contract will be terminated early. Like I said, 8 months is a relatively short period of time so probably you won't need that protection but if you are staying for an extended period of time, those sorts of things are a good idea in the contract.