If you already have a small single burner then it shouldn't be such a problem. I personally use a coleman 424 petrol stove, but there's no way I would recommend that to someone who's new to camping, not unless I wanted to scare them off for ever!
I just thought some of these griddle type stoves can be a bit of a gimmick, but Camping Gaz is certainly a trustworthy brand, & it does look quite useful.
I would recommend you take your single burner along with you, as well as this 3-in-1. It's surprising how much you can do with one burner, but it's always handy to have another one to hand, just in case
As for grills, I think most people only use them for toast anyway, & there's plenty of other ways to make that.
I don't have a grill on my cooker & manage just fine.
Breakfast is probably going to be the busy time for your cooker, not every day but the days you do decide on the full English with a piping hot cup of tea.
(OK, now I'm hungry)
Hope this helps.

4 Canvas tents (various sizes)
3 Plastic tents (various sizes)
& 1 Tin tent (yes, I'm a turn-coat, but it has a canvas awning)
My other passion;
My 1983 BMW 525e
France trip blog