Emma can I recommend you take a look at Fertility Friend videos? Three videos about 25 mins in total give a nice overview of how to recognise your fertile signs.
CM is one of the big indicators, but I definitely think it's best to watch for a range of symptoms to help you be confident you're getting it right. Temperature charting I find very helpful, partly because it makes you record everything on paper.
If you get obsessed interested then this site gives more detail and explanations of what's going on in your body.
I managed to properly spot ovulation by temperature charting. Now that I know my luteal phase length (by counting the days between ovulation & period for a couple of months) I at least always know when my period is due, so I don't get caught out and I know if it's late.
Be prepared for your cycles to be a bit random for now, but if you familiarise yourself with your fertile signs at least you'll be able to Do The Deed at the right times. If in doubt, do it anyway
To reassure you though, the stats out there say something like:
If you are both fertile, healthy, shag at the right time etc there is still only a 25% chance of getting pregnant each cycle.
60% of healthy couples conceive within 6 months with no help.
80% within 12 months.
90% in 18 months.
So it's unrealistic to expect things to happen straight away, but very understandable. I did, and was thoroughly disappointed!