Give J C Cooks a call 01472 210384
If Adrian is in the shop (owner) he will put your right
I don't have an E bike but I am into cycling in a big way and when I asked Adrian about the E bikes his advice was whatever bike you get the motor best motor was the Bosch ones and have a good back up etc.
Most e bikes are speed limited so you can ride at 17mph with the motor doing most of the work to go 18mph you have to do it all (unless you get it chipped) I have heard of MTB bikes that are chipped doing 25mph
For me the best kit you can invest in is a couple of quality pairs of cycling bid shorts and some proper cycling clothing as well as clipless pedals and shoes
If you are about the same size as me I have a few cycling tops I can send you for the cost of the postage.
If you are riding after dark you will need some lights, when I was riding to and from work 16 miles each way I put loads of life raft reflective tape all over the frame, little led lights on my seat post and on my back pack and clipped to my jacket pockets, as well as 2 front lights
You will need a small saddle bag for a couple of spare inner tubes and tools to change them and a small pump most things on a bike can be adjusted with 3 or 4 allen keys
As for MTB tires being less prone to punctures this is not true as soon as you get to a lightweight easy rolling tire they are light and thin, heavy ties are slow and heavy
The best upgrades are tires wheels better components and then frame then repeat
Base fitness comes quickly at first and you will soon be enjoying the ride, race fitness is a big step up though.
PM me you number if you want a chat