An external wall finish is your first line of defence against the elements so you need to make sure that you choose wisely. If you have kept it simple and gone for a plaster finish you will need to employ a plasterer unless of course you feel 100% confident in your own abilities to do a good job yourself. A plaster finish consists of sand and cement with water proofer mixed in. In the hot or warm weather lime is usually added to this mix to slow down the drying process, or else the plaster dries too quickly making it unsecured against the block and will crack from shrinkage.
A finish that has become more popular in recent years is Natural Stone. This is when a layer of natural stone is placed in front of the external block wall. Real stone cladding has to be cut into shapes and placed by a professional stone mason.
It is possible to buy a ready cut stones which would make the job easier and faster. It is also possible to buy stone looking cladding which is really a shaped tile that comes in different shapes and sizes but it is a lot easier to to put into place than stone.
Wood cladding comes in strips that have to be nailed into place and protective sealants have to be applied. On top of the wood a water repellant has to be painted on, this can contain a colour if you wish to add this. This is all to stop the wood from going rotten and must be repeated every few years.
Another finish that used to be popular for years is pebble dash, cement is applied to the walls and a machine is then used to throw the pebbles at the wall embedding them into the cement. In days gone by the only reason that people used to plaster the outside of their houses or use pebble dash was to cover up the bad workmanship of the block layers but now a days people have to work to set standards so that is no longer the case.
Whatever finish you decide to go with do think about the life expectancy . A little bit extra spent now on better quality materials could save you a lot of money in the future.