Hi Louise
Great to hear of another apartment sold on La Tercia so welcome.
Furniture - DFS _ Paul is an extremely nice bloke and will arrange delivery to suit you. He does have a wide range of everything. Second hand furniture is an option also - I do know of some good quality furniture that may be an option also.
Ikea - you can get this delivered and there are services who will do the shopping for you, deliver and set it up and even make up flat packs. Just do a search for Ikea delivery services in Murcia. You can get absolutely everything there - great shop.
Flights - Ryanair flies from many UK airports as you know directly into Murcia and once you have picked up your hire car then it is only a 15 minute ride out to resort. Easyjet also flies into Murcia.
Apartment rental - there are many owners who rent out - have a look on some of hte holiday sites or go to murciagolf.co.uk and put an ad in the apartment wanted section in the classifieds - I am sure you will get lots of answers.
Bits and pieces - Carrefour, Eroski, Casa and Jysk all good shops. Linens and towels at Yorkshire linen in San Javier and there are always the markets where you can get also buy towels and curtains etc.
Hope this helps a little.
Sandra