tea - It depends if they share a room. If they don't it might be a lot easier than you think.
My two singletons (15 months apart) both had their bars taken off at the same time. Developmentally they are quite similar (DS relaxed and DD very physical) and came to the wanting to be released stage at the same time. DS was comforted by the bars and DD wanted to be big. I think I took the bars off when DD was about 12 months and DS 2 and a bit. They shared a room.
It was HARD in the beginning. I had put a gate across the hall (didn't like the idea of trapping them in their room) and a little hook latch on my bedroom door. At night I shut my bedroom with the latch so they couldn't mess with my make up e.t.c. and in the morning the gate being in the hall meant they could come to see and cuddle me but not get into the rest of the flat to be naughty.
In the beginning I tried to put them to bed at the same time but that ended with them just playing with each other and getting out all their toys until 10 or 11 . I eventually changed to staggered bedtimes. DD has always liked to go to sleep quite early so they bathed together then DS watched a video and I read DD a story and put her to bed around 6.30. Then I read DS a story and put him to bed. DD was already asleep and so was boring and DS just dropped off nicely. He always went to bed around 7 depending on the length of the stories and how long it took dd to go to sleep.
It was nice because it meant they each got some time with me separately too. Sometimes DS would muscle in on DD's story but providing you take the other one away to read to them and give the one in bed time to fall asleep then it works a treat.
The wandering is worse if you have 2 wandering at the same time, in the same place and egging each other on. I think the way to deal with it is to set a bed time when they are tired and to either keep them trapped, safe and bored so that going to sleep is their most attractive option or just keep returning them to bed without giving them any attention until they get the message. This doesn't work at all if they share a room though. They just laughed at me and played together when I tried to put them to bed together! lol
Snowdonia is lovely. My parents have a holiday flat in Porthmadog so we spend a lot of time there. I love the Ffestiniog Railway. The Santa trains they do there and on the Welsh highland in Caernarfon are really lovely at Christmas time. Why did DH think 'me time' for you included the children? lol That is rather spectacular stupidity! I'm not sure he'd consider it 'me time' for him if he was dragging the babes around on the back of his bike!
Are you more relaxed now after a weekend with your mum?