Parties banding together to make a government is still a problem. What if every party but Reform says they will join together and have more votes? It won't function but it will hold power won't it?
Coalitions are
only possible if no party receives a majority in parliament and can
only be created by the largest party in parliament, and otherwise the number of MPs in parliament at any one time will always be smaller than the party in charge.
Our system is salvageable thanks to both inter-party and in-party conflict that is mostly absent elsewhere, as well as lacking any blockages or hindrances besides: Civil service, FPTP, and maybe the House of Lords (who'll probably be in their best behaviour if Reform gets in since Farage isn't shy about wanting it gone).
Rather than all the parties coming together and attacking Reform, all the parties continue to attack each other, which is optimal. No dogpiling the one outsider who stands a chance like in France or Germany. The UK parties are also more at odds with themselves than you'd see abroad. Labour's recent stunt and rebellion would be unthinkable in Germany; it's also the reason I have any hope for Reform at all since this is common enough that regardless of what Farage wants, if enough Reform MPs oppose him they can just get what they want anyway, just like the Conservatives did once upon a time with getting the Brexit referendum (Mogg and his faction wanted it, Cameron and his faction didn't).
The biggest problems I see are if Reform don't become the largest party in parliament at all at which point we may - if we're luckly - get some token immigration fixes by whoever leads which'll just keep our decline ongoing, or they become the largest but refuse to coalition with parties they consider caustic (assuming they get seats (Homeland, Advance UK, etcetera) and get subsequently bound by whatever party they make a deal with. The third big consideration is if they get in and still do
nothing.
If we end up in a situation where our problems still remain unaddressed, then I think the civil unrest of the scary sort becomes a major possibility. I just think right now it's less likely for the UK to be within the next 10 years thanks to how our system works.