Apologies if this is a stupid question, but I'm pretty new to gardening and a little confused.

I live in the Manchester area and have various plants (Tomatoes, Runner Beans etc) growing inside. According to the seed packets I need to put them outside when there is 'no longer a risk of frost'

When is this time?

According to this page from the BBC, I appear to live on the line between 'early to mid May' and 'Mid May to early June'

According to this discussion

My observation in Manchester is that frosts in May have been extremely rare and always mild for a number of years now and I plant out in early or mid-May with an eye on the weather forecast.

Looking at various weather forcasts, it seems that this coming Sunday may have a zero degree reading. Does that mean a frost?

Sorry for such a long post, but grateful if someone can help. I don't want my 'garden' to die.

Paul