Hi Polar,
I tend to agree with all the advice you have been given i.e. try to do the IR full time. However, since I did it sort of part-time, I'll tell you how I did it. I got the writtens out of the way but then had a long delay trying (unsuccessfully) to save enough money for the flying. In the end, managed to increase the credit limit on two credit cards and used those. I found it extremely difficult to get a block of time off (I'm self-employed) so I did all the sim work at weekends. (I could only manage two sessions a day totaling 2 to 3 hours) I did try 3 sessions one day but I was just wasting my money on the third session, I was mentally too exhausted to gain much.
When I had finished all the sim hours the plan was to go back for the flying a few weeks later. I found a school who were prepared for me to do blocks of four days a week from Friday to Monday which I thought would be almost as good as full time Monday-to Friday. I was wrong..... My progress suffered because I underestimated the difficulty of working longer than normal days on Tuesday to Thursday, then driving 200 miles to stay in B&B followed by 2-flights a day IR training for four days followed by a 200 mile drive back on Monday nights and back into work the next three days.. and so on.
Looking back, it seems obvious that I was overestimating my stamina and ability to learn under these circumstances. Fortunately I did eventually get a first time pass, but I had previously blown more than one F170A checks.
Like others have said, it might be cheaper in the long run to hand in your notice, or at least take all your annual leave in one chunk before trying to do the flying. I don't regret doing the sim work part time first though, getting that out of the way certainly helped.
By the way, I've not paid off the credit cards yet. All donations gratefully received.
Finally, Good Luck !!