How much would postage be...

Go on one of the sites and enter the size and weight of the package and it will give you a price. Be careful to ensure you've got your money before sending anything abroad as scammers from West Africa do operate from the likes of Spain and Portugal. No Western Union transfers remember.

I used this place to send a bike to Italy last year:
http://www.directcouriersolutions.co.uk/bicycles.php

Iirc the cost was around £80 with suitable insurance.

I used a big bike box, and just removed the handlebars.
As it was a bike for my brothers gf, I spent a couple of hours packing it, and built a wooden frame around the rear if the bike, which protected the rear derailleur.

It made it there unscathed!

Try Shiply.co.uk

Hundreds of small to medium courier firms will see your business (bike from say, London, to Lisbon in Feb) and bid for it.

We use them all the time to get big stuff sent from UK to France. Can be surprisingly cheap if a courier is just looking to fill space on a part loaded van.