If you have only just moved in, that will explain why you hadn't noticed it before. If no one is around to call for domestic hot water or heating, no condensate will be produced.
As per @Nige F 's post, I would be tempted to ask the plumber to rectify it for free or at cost. Again, I am not a plumber, but he might be in a world of pain for signing it off prematurely.
Based on what you say, I very much doubt that it will have harmed anything.
A quick Google search suggests that up 2 to 3L of water can be expelled per hour (no idea how accurate that is though).
Yep, just sent him a message telling him I've been in contact with GasSafe & was told it should have been fit by the engineer and asked him to come round to rectify it.
I should say it's 100% not dumping out litres of water per hour it seems to fire hour like every few hours and it isn't a lot of water.