Mould under sink and rusty gas meter

Two questions. Is this mold anything to majorly worry about. It could have been there many years without us even knowing. Also the gas meter is getting rusty. Their is no leak on the sink. It is cold under here which I'm guessing its condensation on the pipes causing the mold. Also there is an outside tap where the mold is that blasts on the wall at times. I was thinking of putting some plywood on the floor and cleaning the walls and painting it with anti mould paint. Does anyone think this would help? Also let me know if its unsafe. Also has anyone any idea how I can tidy up the monstrosity and make it look decent

Certainly worth getting it checked out as it appears to be excessive moisture. Is there a tumble dryer in the kitchen? As for the gas meter, it could get worse and they shouldn’t be installed in high moisture areas - have you smelled gas in the property at all?

Damp area under the sink is very likely a chronic leak. Tie bits of kitchen roll round the waste, under the taps, and any other joints you can see. Observe which become wet.

Correct the defect on your outside tap.

The outside tap no longer leaks. It's just say I'm finding paintbrushes the water starts splashing and gets on the wall. I will tie kitchen roll round but I have ran water and checked all the waste. The only thing I can think of is water going all over the sink when kids are making drinks etc and it getting in behind the cupboard door. The mould could have been there since we moved in as the outside tap constantly leaked then. Is it worth painting with antimould paint to tidy up? Il give the gas meter a wipe but not too much of a scrub. I may plywood round it as well to protect it a bit from any dripping water from the sink or would that be frowned upon? No smell of gas or sign of any leak at all

Quite whats going on under the sink looks odd.
Could you stand back and pic all the plumbing and gas arrangements under the unit, and a pic of the work/sink surface? And a pic of the outside of the wall?

There's a leakage under the sink in the corner where i assume that the work top was cut out?
There's also what appears to be damp in the wall - is it from the work surface leaking down and/or rising damp in the wall - i cant tell?

Looks very similar to mine, even down to rusty meter, propped on a brick and always ok with gas people who said they're virtually indestructible. I did find that the meter (cold lump of metal) and the lead and copper pipes attracted a lot of condensation. Any leaking pipes should be fairly obvious with a handful of loo roll. As above, most likely cause is sink/worktop seal.
I moved the meter, otherwise I'd have probably core drilled through the wall and fitted a small vent.