What have I done?

Help, help, help! What have I done? I'm 34, married with two young children and studying full time for a Masters for the next twelve months. A few weeks in and I'm ever so slightly in awe of my fellow students: gorgeous, young and clever. Then there's me. It's been so long since my chemistry degree that I can't remember anything much about it. I can't even understand my doctoral thesis any more. And by the time I'd negotiated and agreed the childcare plan for this term with husband, childminder, fellow school mum and mother-in-law, I was worn out and my brain hurt.

It seemed like such a good idea when I first thought of it. After a few years with small children for company, I wanted to exercise my brain again and the MSc in science communication at Imperial seemed like just the ticket. I dreamt of working at home in those halcyon hours while the children (5 and 2) were merrily amused at school or pre-school. Well, there's been a lot of reading and learning to do and my brain is stretching in unexpected ways. I even had the mental energy to rent a thriller - The Interpreter - at the weekend, instead of my usual sort of no-thinking-required romcom. My first assignment is complete and handed in. But the big surprise has been how much fun I'm having.

Last week my course-mates and I made four Question Time-type ten-minute 'as live' TV programmes. Just over half of the group operated the cameras, sound, and chose which camera shots to use. The rest of us pretended to be erudite panellists and discussed the ethics of designer babies, human drug trials, teaching intelligent design in schools and the North Korean nuclear test. There was a lot of laughter as we watched the end results. I think the Question Time team can rest easy in their beds for a few months yet (despite not having matched our scoop in getting Kim Jong Il onto the programme). Some of our discussions were more confrontational than others but I don't think any of them lived up to these classic Question Time moments.

Another highlight was a seminar from the evolutionary biologist Armand Marie Leroi on his experiences of writing a popular science book, Mutants, and writing and presenting two TV series Mutants and What Makes Us Human?. Some of the heartbreaking pictures he showed us from his book were hard to take and after reading up on 'designer babies' or rather, on the technique of pre-implantation genetic diagnosis (PGD) for my role as a Question Time panellist, I found myself ever more grateful for the blessing of two healthy children.

PGD is a bit like IVF plus. It works like this: a couple know they carry a faulty gene they don't want to pass on to their children. Just as in IVF, eggs are harvested from the woman and the man donates sperm for her eggs to be fertilised in the lab. One or two of the fertilised eggs are implanted into the woman's womb in the hope she'll become pregnant. With PGD, there's an extra step or two before implantation. When the fertilised eggs have each developed into embryos of eight or so cells, one cell is removed and its genetic make-up tested so that embryos free of the faulty gene can be chosen for implantation.

Our 'Question Time' discussion was only ten minutes long and could only touch on some of the ethical issues raised. What does 'playing God' mean when we routinely make decisions about whether to try to conceive this month or not? What would I do if I discovered I had a 50% chance of passing a genetic disease on to a child?

A younger friend of ours came to stay recently and helped out with childcare while I was settling into the course. After twenty-four hours she declared she'd never have children. Clearly I'm better at dwelling on the lows of motherhood than the highs. Getting the children up in the morning, doing the school run, wiping their noses and mopping up the sick in the middle of the night are all more in-your-face than the hard-to-convey subtle joys of cuddling up to read a story together, sharing big hugs, seeing them grow and understanding Child 2 when he says 'Mick-mick' (he means Baby Pom from the Fimbles).

After a week our friend had changed her mind. She might have children one day. But not while she was studying. That leaves me just where I was at the beginning – what have I done? Help, help, help!

This post was previously published as a student blog for The Times online