Yes. You can drive anything up to 3 1/2 tonnes. If you want to drive heavier up to 7 tonnes you have to have a medical and jump through a few hoops to get it, like your consultant seeing at least 3 months worth of BS readings (self testing ones), but it is not so hard to do.
But yes, a standard Transit van under 3 1/2 tonnes is covered by your ordinary licence. Nothing changes on your licence except the withdrawal of the 'over 3 1/2 tonne' bit and the fact it has to be renewed every three years. And that is free to do by the way.
ps: when I wrote that above, I hadn't noticed that you are an old hand at diabetes, not newly diagnosed, so I'm sorry if you thought I was treating you like a newbie.