Nigel Farage becoming an MP is more like Trump becoming a member of the House of Representatives, I think. Though the Commons has the final say, and, unlike the Senate, the House of Lords can’t overrule the Government, they can only suggest amendments and cause delay. Ultimately the Government can reject the proposed amendments.
Usually, the ‘checks and balances’ provided by the House of Lords works well and amendments are given proper consideration
There won’t be a coalition between Farage’s Reform and the Tory Party. This has been suggested by Tories on the right of the party, but it would never be accepted by the ‘One Nation’ Tories on the left. I think the party would be likely to split in such a scenario. It is possible that more Tories will defect to Reform, though.
With Farage only winning 5 seats, though, I think it much less likely that the Tory Party will link with Reform. They have enough MPs (121, I think) to be a workable opposition on their own. Though nobody knows what direction they will go in, whether to the right or the centre ground. They’re in disarray right now.