Need some advice as I'm thinking of replacing my side gate never done it before. The first photo what tool is best to remove the big piece of wood attached to the fence? as its nailed in.

On the 2nd photo If I were to take the wood out of the brick wall and place it in another position would I have to drill a hole through it before putting the screw in? or just drill the screw in straight away?
Any other advice would be much appreciated.

1) if wood nailed to fence it should prise off with crowbar as its only fixed in a max of 2 inches into the fence. Not so easy if they have used ring shank nails. I had to fix a similar piece of wood to get a fixing for the gate catch..Its there for a purpose.
2) if you take the door frame off the brick wall you could use the same holes in the wood.(use new through frame fixings..screwfix or toolstation about £3 for enough) You will find it very difficult to get the frame fixings out with just a screwdriver. Crow bar or jemmy but you may damage the frame. You will either need to drill hole in brickwork or you can get special fixings that drill into the brickwork (they often have a different head than normal screws..you will also need a hammer drill and suitable long drill. Only couple quid at Toolstation.
3) new gate...pay a little extra for a 10/15 year guarantee one. If you don't get the gate to the exact width you may need to cut or plane one edge...another power tool needed.
good luck

If you are in or near Wallasey I can come and get it off tomorrow Sunday no charge.

Oh well done you Salty, that's a very nice thing to offer. You sound a kind man and as they say a good egg.

Thanks for the help. Managed to get it done.