Thanks very much all for your advice. In response to your questions/ thoughts
- I need to make 2 x base units (900mm x 500mm), 2 x chest of drawers (400 x 500), 2 wall units (450 x probably 1200mm but TBD)
- I am trying to avoid using a router (mainly because I haven't had much luck with one to date) so was planning on using butt joints to connect the pieces of the cabinet together
- what size screws would you suggest I use for the butt joints?
- unfortunately I don't have a sash clamp but do have some G clamps and some quick release clamps like these (https://uk.rs-online.com/web/p/clamps/8793016). Also have a load of off-cut timber/ boards etc. Was hoping to rig something up to save me buying the sash clamp just for this project - any ideas?
- unfortunately we have decided to have the type of doors which are framed inside the opening rather than the kitchen door type style where it sits on the front of the carcass. I was planning on putting some 18mm timber to frame the door and to hinge the door off so hopefully any slight issue with the cabinets can be hidden with the timber and ensure the opening is square for the door

and some follow up questions
- The 900 base units have double doors but was hoping to not have the vertical bar up the front. Will the 18mm ply be ok without the support?
- I have some 12mm MDF and some 12mm ply which I was thinking of using for the middle shelf screwed in through the sides. Will this be sufficient?

Thanks again all - would appreciate any feedback on this.

Lee.