I see this is your first post so welcome.
Your question is difficult to answer. I do not know if you are 10 or 50.
Pink foam for beginers
Joel Logan Cavern & Mine Tutorial 01 - Tools & Supplies
https://www.youtube.com/watch?v=qM0vLhZB5QMHow to hill
https://www.youtube.com/watch?v=KgbPc1dOWCAalso with hand tools
https://www.youtube.com/watch?v=_DsTFNU7-RsHow to brick
https://www.youtube.com/watch?v=SPFTiimqe_sAdvanced
http://hirstarts.yuku.com/topic/7133/Wa ... 0v3F_ldWSohttp://www.hirstarts.com/Or you can copy this one
http://www.paulsmodellingworkshop.com/i ... bumPictureThe front entrance details are made from slate. Everything else looks like foam. I would use Hirst Arts blocks for the interior.
This bondo grader is very useful for carving foam. I like drywall filler better than the plaster Joel uses. I would not use white foam. That is why I posted Joel's tools and supply link first.
I hope this information helps. If you are in the UK someone local will help you locate supplys