Hi Dave ,
I have a boat in the marina at Amble but use the slip frequently , there is a roundabout at the top of the slip , go round it the wrong way and then reverse down the slip.
You should pay the harbour fees for the use of the slip , I can't remember exactly but it's about £12 a day or £52 a year (my marina fees include the harbour fees so I forget now what I used to pay) the harbour masters office is on the quay side next to the car park , you can pay the day before or shove the money through the letter box if you are launching early.
It's a long narrow concrete block slip and very muddy at the bottom at low tide , there is nowhere to tie up your boat if you are launching alone and the car park is a hundred yards or so away from the slip so you need to anchor your boat whilst you park the car (free parking). The slip is very gently sloping so if your car struggles on this it will struggle anywhere.
If your boat is on a bunk trailer take a rope to tie between the car and trailer so you can leave the car on dry land and push the trailer out to deeper water till the boat floats off. Mine now is on a roller coaster and it's a doddle , water half way up the trailer wheels and off she slides , my last boat was on a bunk and i had to use the rope to keep the car out of the water , there are no nasty drop offs or anything on the slip so it's safe and easy to do.
Keep to the harbour wall(south) side of the river as you go out , the north side shallows right up to a sand bank.
Fishing spots ,anywhere between steel bush and coquet hole behind the island or head south , find northern hill on your plotter and drift from the shallows out over the deeper water till you hit 60ft or so then motor back up over the shallows and repeat from a different spot , watch for sudden drop offs , they usually hold fish.
Further south again to Cresswell skeres , same again , find the shallow water , park on top of it and drift off over the deeper water , it's a vast area of hard ground and there should be fish there somewhere.
This coming weekend you should be able to launch any time in the morning as low water is at 3.30 sat and 5 sun and nearly 2mtrs. Coming back in I personally would stay out till dusk , if that's too long then I'd be looking at getting back in for no later than 2pm sat 3pm sunday. but don't blame me if I'm wrong and you have to wait till the tide comes back in lol.
Let me know if and when you are going to give it a try and I might see you out there.
Ray