It's too soon to predict exactly how the British House of Commons is going to turn out. It's quite likely that it will be a "hung parliament" however, where nobody has a majority but one party (the conservatives, likely) have a plurality.
Considering this is the case in Canada as well, and has been for a while, it does raise the question about whether or not this will become the rule of thumb for Westminster systems in general. It also suggests that the main argument for FPTP systems—that they generate stable two-party systems with clear winners—simply does not apply anymore.
At best, you can hope for stable coalitions, and you're as likely to get that from a proportional system. Considering there is literally nothing else that justifies FPTP, the lesson is clear.