Advice on plastic hen houses

Hi Grumblepuss and welcome. Like you I had my first attack of redmite last year too which prompted me to buy plastic. I started of with an eglu classic (2nd hand) but having so many chickens (40+) I couldn't afford enough eglus for them all so I looked at various others. I live in a very rural area so in the end settled for one that looks like a pig ark by Solway plastics (I saw these at the pig and poultry show so had a good look around to see how they were made and put together. However they are big - approx 5 feet by 4 feet so may not suit your 4 birds although they do do smaller ones.
There are plenty of other makes though - green frog (didn't really like the doors of these), doodle houses (quaint but too white),
little barn chicken coops - look ok for just 3 or 4 hens (http://www.littlebarncoop.com/), chicubes which just look like packing boxes (http://www.chicubes.co.uk),
durham hens poultry supplies spoilt for me as they have wooden perches (on ebay),
and also on ebay is a company called bubbles kitchens who make plastic coops - never seen one of these in the flesh though so no comment on them.
You also need to consider if you want one with a run or not - not all have runs so you may need to make one 

ooh I like the Solway Plastics range...... look so easy to clean etc tempting 

to true, luckily for me mine can be steam cleaned with an industrial steamer and at work on a hard surface. Also to anybody with redmite don't put the bedding in your compost as they will soon crawl out of that as well and back into your coops