Hi Bob. First off let me say that a clogged compartment drain with ice in it can be a real pain. Portable hair dryers don't work because the water insulates the ice. You may not like the answer here but this is several decades of hands on exerience speaking. So here goes......
1. Unplug the unit.
2. Empty the contents of the freezer
3. Place a fan blowing into the freezer section for well over 2 hours.
(THIS MAKES A MESS so be ready with rags and a mop)
<After external fan period and mess period>
4. Get yourself a single strand of #14 gage household electrical wire with insulation. Strip the end of the wire about 1 inch on the very end of the wire, fold it back on itself so that there is not a sharp end. (Flat tight U Loop) and start pushing it through the drain. If you hit any blockages or elbows try bending the loop just slightly. (Just do not force it really hard as you may detach the drain tube from the freezer compartment. Measure the distance that you have traveled the wire through the drain. It is pretty much a straight shot top to under the bottom of the chassis at which point there are some bends. Once you know you have reached the bottom of the chassis... pour HOT water thru the drain and observe the lower catch tray in the bottom of the unit checking for water flow from the tube. Often the plastic tray in the bottom of the unit has water in it just as a result of normal defrosting. The end of the cabinet drain tube sits in that tray. Over time the dust and lint that collects forms an ugly goo in the plastic tray. That goo eventually dries out and can also encapsulate the end of the drain tube. Make sure to clean the drain pain and the end of the drain tube during this process.
If you have problems and there is water in the drain that you need to remove; a roast baster works pretty good for removal of the water near the drain.
While you have it manually defrosted do your best to clean the drain top and bottom. These 2 areas are where most blockages occur.
Once your all done cleaning... wipe the bottom catch tray dry.
Pour a measure amount of water 50 ml or so in the top drain.
Check to make sure you get 50 ml at the catch tray. If you do not get close to what you put in.. at least 45 ml. Then there is a problem with the drain tube. i.e Hole, pinch, fold etc.
Getting the unit to room temp... (Fan) and letting the room temp defrost the ice in the tube is the best way to clear this. Slow process but a must do. There really is not a fast way to do this. If you don't have access to a piece of wire... a larger LONG plastic ZIP / Cable / Spot tie (Like they use for handcuffs) will work well also.
Just a final note. I looked up your unit parts via Hotpoint UK.
There are 116 parts available and the drain is not listed.... be careful.
Thanks for choosing FixYa.