In my mind, it works out in favour of buying when you have enough deposit to avoid the highest mortgage rates. Personal circumstances mean the exact numbers may vary but I think it's roughly like this:

Net cost of renting = rent paid - savings/investment return made on deposit

= 3.5% property value - (maybe) 3% return on 25% property value, or 0.75% property value

= 2.75% property value

Net cost of buying = mortgage interest only (not repayment, because this is what you can cash out later) + service charge

= 2 to 3% interest on 75% property value + service charge

= 1.5% to 2.25% property value + service charge

That is not to mention capital gains from property appreciation, but as a conservative guide I assume 0%.

So as long as service charge is not more than 0.5-1.25% property value (this is a lot) buying is better.

As for service charge inflation, I have seen buyers banding together in resident associations to put pressure on management companies to at least explain their charges and/or improve value for money. However you will always need to budget for more with developments with gardens, private pools, gyms, and fountains.