Hi AllI am a complete gardening novice

Welcome to GoY...

We need a photo Christinef or at least a lot more info such as is that six foot fence open with gaps like wrought iron or closed like a fence panel ?

Everything needs a little care and attention especially if you want it to look nice all year.

In sun or shade? Better if you can say which way it faces (north, south whatever) but at least sun or shade is better than nothing. Also what part of the country are you in (for a plant hardiness point of view)?

Hi Christine & welcome. Sounds like great potential you have there! With careful choice it will look lovely. Did someone else put up the fence for privacy perhaps? (a reason for asking) seems mega high... how long is it anyhow?

Hi Christine, 7 miles East of Manchester could put you quite high up near Ashton-u- lyne at the foot of the Pennines, near Saddlworth Moors ? No need to answer that directly, it just gives other members an idea of the conditions.

Hi Yes I do live nearby Ashton under Lyne.
The only photo I could find to upload earlier today was before we had some patio work done. This is how it looks now!
I really like trees but haven't a clue what might be suitable and fairly quick growing because as you can see there is a lot of bare fence and wall.
We also have a very large tree (possibly Ash) which overhangs the bottom of our garden.

If you're referring to that wall with a fence on top at the end of the garden, and you wanted to plant something actually in the wall, you're a bit stuck for variety because of the shade from the overhanging tree and the fence behind. You won't be able to plant a tree within the wall, but can plant one in front of it, in the ground if you like.
Amelanchier Ballerina or Prunus amanogowa might fit the bill for the tree - I'd be inclined to choose put up with anything, grow more or less anywhere plants in the wall itself such as Ajuga reptans, Campanula muralis. They're okay as wall subjects, but in a sunny, open spot, such a wall would present a great opportunity to plant really attractive, trailing plants, but given the environment there, I suspect most of those would just die, since the majority of them are alpine sun lovers.

have you thaught of perhaps making the wall pleasant to look at instead of just hiding it maybe . perhaps a tree each side as a kind of frame . i think myself something quit regimentle like some of these realy thin strate connifers . perhaps a waterfeacture like you put on the wall and some of that roll on split bamboo etc . i wouldnt hide the bittem wall as thats nice on the eye . anyway just a thaught and ofcourse some nice lighting and a little seating area .i can see lots of possabillities id love a tall wall like that in my garden lol .

Could the panels possibly be replaced with open trellis type panels ?

I know the trench is 2 foot wide but,I was wondering how deep the trench in the wall is? I was thinking a row of carpet or bush roses and some evergreen climbers.

It is the fence that is the main problem, you have done a great job on the patio area compared with the last photo by the way.

If you were stood facing the fence which way would Manchester be ? So we can find out the way your garden faces.