I would say on point 2 - don't expect to complete PPL in a few weeks, especially not in UK. Book every available day you have, and expect 50% to be cancelled. Also, book early. I once had a lesson and once landed I went to book in for the next lesson, and I had to wait 7 weeks. With instructors thin on the ground now due to the market buoyancy and everybody wanting to train, I expect this wait would be longer. Plan very early and ahead if you can.
On the CPL and IR - I did both over the course of 5 months while working a full-time night job (Tues-Fri 1900-0530) - its very doable around work if you have the capacity. I flew Saturday PM, available all Sunday and Monday, and Tuesday AM. On a given week I may have only flown twice. May not need to quit the job, can earn and do your training at same time with a reputable modular school!