Yes its me again playing the age card,i always thought i could record 2 programmes and watch another but no i cant, did i do something or has this always been the case? any advice would be appreciated
It all depends how many tuners your model of Humax has. I suspect that your Humax has two tuners and you've misunderstood the fact that you can record two programmes and watch a RECORDED programme ie, NOT a live broadcast.
You can record 2 while watching one already recorded or you could switch the input from the Humax box back to "DTV" (called so on my set) to watch a 3rd channel.
Bhg481's answer is entirely accurate as long as you're only using the twin tuners in the Humax box (and watching a signal sent from that box's output to the TV).
However your TV set also has its own Freeview tuner built into it. So, as long as there's an aerial connected to the relevant socket on the TV (possibly using a fly lead connected to the 'Aerial out' socket on the Humax box) you can use the TV's tuner to watch a channel which is independent of those being recorded.
i.e. once you've got your Humax box set up to record two TV programmes, use the TV set's remote control to change the signal source from 'HDMI' to 'DTV' (or or whatever 'normal telly' is called on your set). Your Humax box will continue recording the two programmes which you've told it to do but you can then select another channel to watch on your TV set (just as if you were using it without even owning a Humax box).
You should have an input option labelled tuner, antenna or similar. It will NOT be AV1, HDMI1 or SCART. Try all inputs in turn until you get a picture.
It'll be whatever looks like it might mean 'normal TV'.
As has been mentioned, many TV sets refer to 'normal TV' as 'DTV'. (Digital TV). However others might label it as 'RF' (radio frequency), 'Ant' (antenna), 'Ae' (aerial) or something else. Simply keep trying anything that looks likely until you find the one where you can change channels using the TV set's remote control (rather than with the one for the Humax box).