I'm backpedalling furiously, QCAD seems not that bad! One of the features of DS I used a lot was the ortho button, I could then restrict lines to being horizontal or vertical (most of them are in reality) and either draw them a set length or between 2 clicks. If I keep looking I might find a similar feature in QCAD, at the moment I have to do 2 menu clicks, one to select the line menu, 2nd to say what type of line.
The £25 annual fee seems to be to keep on having updates, otherwise it's a one off 33 euros +vat, which is well within budget. Birthday coming up soon, so I'll probably treat myself
Postscript, I've just found that right click brings up the last few commands (not sure how many yet), so drawing lots of vertical and horizontals will be much quicker