@spenceey we explored brick slips years ago when I had the same idea. I got samples and everything, the issue I had is that they just looked too perfect and I felt it would have been an obvious "fake" brick wall.
We went down the route of taking everything back to bare brick, which was the most horrible job I have ever done. This was in Cardiff where a lot of internal walls in older properties use a mortar mixed with slag from coal mines - so it was black coal dust.
I had to repoint everything then using lime which took ages but the finish was great. We sold the flat about 6 months afterwards and it was sold again 2 years later and the wall had been rendered. I nearly cried.
Honestly, I probably wouldn't bother unless you absolutely want a bare brick wall, and if you do I would do it properly (i.e go back to bare brick).