What @gabsdot45 says is bang on the money. It's children who are the ones with rights and whose rights are paramount, as enshrined in UK law.
It's also true to say that the rights of the child to a home, food, clothing, nurturing and loving care don't come courtesy of a biological tie. Biological parents have been known to do unspeakable things to their children.
Nor do they come care of the parents' economic circumstances. The idea that IVF treatment should be a privilege only available to those who can write of £thousands on fertility treatment - or, for that matter, should be prioritized for higher-end taxpayers - is really pretty repulsive.
I'm estimating that the money we've spent on fertility treatment, Chicago blood tests and myriad intrusive examinations during our 10-year effort to have a child wouldn't have left us with much change from £70,000. Incidentally, I'm a higher-end taxpayer too, and took nothing from other taxpayers toward the cost of this treatment. What difference does that make? Absolutely none IMO, and fertility treatment should not be limited to those who are in a similar position.
Incidentally, in the UK the patients' GP is legally obliged to fill in a form relating to the potential wellbeing of any child conceived by IVF, before the clinic will accept them for treatment.