Electrical issues foot well leak during winter months

There are a few things to mention regarding this problem And I will detail as much as possible.
Firstly, I have replaced the alternator about 6 months ago after car completely went, checked battery and needed the alternator so changed it and all was fine.
The electrical issues I have now were present before the alternator change as well.
Firstly, when I turn ignition the radio, dash, windows and electrics do not kick in straight away all the time. Sometimes they do but a lot of the time it takes 5-10 seconds for radio and dashboard to kick in. Then after a while and which pretty much started this time last year I would get the same thing but when driving, the cars electrics would completely cut out along with a kaput/pop sound which sounded like a bad electrical disconnection. Not super loud but loud enough to pop! And then it would just kick back in pretty much straight away with all warning lights on. Then back to normal. Now this has started happening very erratic when driving. It happened 7 times on a 3 mile drive 2 days ago.
Now to add to this, and what I have only just found is that my drivers side foot well near enough where the wire loom sits it is soaking wet under the carpet. I checked around windscreen and both sides of the bulkhead? They are plastic part that window wipers are on and that attaches to the windscreen are bent upwards. They were full of moist dirt and it seems water could easily get through.
I am hoping the water in foot well could be causing these electrical issues. I will also check all fuses, wiring from alternator and battery terminals.
And lastly the electrical problems didn’t happen really at all in the dry summer months.
Any advice would be appreciated.
Thanks,
Mal