It's time to divide it. You can easily divide it into two or three smaller plants for suitable pots. Take it out of its pot, wash off soil from the rhizomes. Separate the rhizomes & replant them into smaller pots - two or three rhizomes per pot. Re-pot with fresh new soil, a little fertilizer and they will have a new start on the new year. You'll end up with several smaller plants you can give away or toss into the compost heap.

No chance of a photo I supposes? Otherwise, what variety of fern is it, and how big's the pot its currently in? Is it a hanging pot?

have you thought about the plastic patio pots, they can be very large. there are some massive plant pots that are used for trees.
as asked do you know what fern it is?

welcome to goy too :o)

Have you tried several different suppliers? If you had your county on your profile maybe someone could suggest a good place to try?

Many people today are shopping online. Amazon.co.uk has a good selection and good prices/bargains. Here is a link:

https://www.amazon.co.uk/s/ref=nb_sb_noss?url=search-alias%3Daps&field-keywords=flowerpots%2C+planters

Assuming no joy locally try http://www.worldofpots.com/ who specialise in big ones. (very attractive ones too)

Thanks for that link Stera, I am always on the look out for a good pot!