I'm struggling to find the right bearing for my front wheel, wondering if someone can help

It's an E1900 wheelset, 6 bolt discs, boost spacing. The front wheel has a 15mm axle through the fox shock.

I can't find what bearing I need annoyingly. Have been googling and have found a useful document but my hub isn't on there and I can't work out what bearing I'd need. The doc is here - https://pictures.dtswiss.com/uploads/WX ... EN_001.pdf

Can anyone help please?

Why not get to the bearing you have and check the markings on the side. Inlut that info into one of the online bearing sellers (Wych, BearingBoy etc) and get the appropriate one... Maybe even upgrade it at the same time by going NTN or FAG/SKS

Because I can't then ride the bike and my other MTB needs a brake bleed. Although I'm off the bike for a good few days due to a crash...

I was hoping to get the bearings and then do it myself one evening. Local shop said it'll be £15 to do it but I fancy giving it a go myself

you should be able to pull/unscrew the bearing cap with the wheel out of the bike, and clean the rubber bearing seal and read the bearing number. You're looking for a number like 6008 2RS. Often the 6 and 8 look very similar so take care. Should take 10 minutes max.

If the local shop said £15 then...

A. it might be easier to pay them

...but....

B. They won't be using decent bearings!

Ps at the end of the doc there are measurements for the bearings, if you can find the right hub and out those in a breeding finder it'll give you the part number

There is an interactive online support parts finder here:
https://www.dtswiss.com/en/support/product-support

Using the information you have given it could be Ball bearing 6902 Ø 15/28x7mm but don't take my word for it.
You have to dig for the information but it is there.