I'm not an electrician but I don't know if you are aware that Wylex/Crabtree do RCBO's that are Type A with a switched neutral. Wylex themselves describe them as single pole with switched neutral [1P+N], but retailers market them as switched DP or just plain DP and forum members describe them as DP. So I don't really know if they are truly DP, or in effect DP, but you'll know better than me on that.
It's their new "NHXS" range, which you'll find in Toolstation.
There is a sheet on Wylex's website about the RCBO's.
I also found a thread on this forum, dated 19 July, which suggest some other options too, it is called "Recommend me a small cu with dp mcbs rcbos" - thread number 175774.
I'm afraid that I can't link to any of the external resources anymore due to the restrictive spam filtering.
I don't know if this is of any help to you.