So let's be clear.
Are the carriers absorbing significantly more manpower than the ships they're replacing? By design, no - they're broadly similar in complement to CVS, of which we were running two up until 2010. They do require substantially more bods than Ocean and one issue appears to be that someone has made an assumption / taken a savings measure on naval manpower when we chose Ocean over Illustrious to run on as LPH, without thinking it through. That is hardly an intrinsic effect of the ships though.
Then you get into which budget all this stuff comes out of. If - as many postulate - "it's all because of the carriers", then you'd somehow expect to see the service personnel budget shrink in proportion to the EP. Unfortunately, this doesn't appear to be the case. Main Estimate budgets for service personnel (civ per is a separate budget) were £8.7Bn in the 13/14ME, £8.8Bn in the 14/15ME and are £9.5Bn in the 17/18ME. Set against a reduced number of people. Go figure.
Likewise equipment support. The figures for those three ME years are £6Bn, £6.4Bn and £6.4Bn respectively. You'd expect the latest ME to be higher, but is that attributable to the carriers? Unlikely - not least because they're not yet in service and therefore don't - yet - affect that budget.
The fact is that the carriers are barely affecting the budget - certainly compared to other platforms / services that absorb significantly more. What is actually happening is that the defence budget as a whole is not increasing in line with "defence inflation", which is leading to a resource squeeze across defence. This squeeze is being attributed to "the carriers" primarily because they're new, they're much bigger than what has gone before and therefore everyone assumes that they're consuming much more of the budget. Which doesn't actually appear to be the case - there would still be significant pain and grief across the board - the big drain on resource is not associated with large grey ships however much people would like it to be.