I am some what bemused by folks who are starting out in this industry arguing to folks who have spent several decades in the industry that we don't know what we're talking about.
Nothing we say will stop you from spending a fortune and trying your luck. I wish you well. However, there is a huge difference between what the sales people will tell you at any flight school (especially L3, OAA, FTE etc) versus reality.
Historically, as in the last 10 years, the vast majority of 250 hour pilots who have obtained a reasonably well paid jet FO job in the UK have come from the above 3 flight schools.
The industry is cyclical and particularly sensitive to the economic cycles. Right now there's a hiring boom. In 2 years time, there may well not be. (Probably lay offs if history's lessons are to be heeded).
A single 25 yo has time on his/her side to weather the troughs, a +40 yo does not.
As stated many times, if you can afford to burn through £50K and more, earn £15-25K for the next 5 years without negatively impacting your family's life, then great, go for it with our blessings. If you can afford £100K+, earn nothing while training, and earn £20-£30k for 2-3 years (and pay rent/loan/mortgage) and not negatively impact your family, again, go for it. These are averaged numbers, and assume you'll get a job soon after completion.
If you don't you'll need to budget 6-12 monthly IR checks to keep yourself current. That is expensive.