Starting problems - starter motor (i think!)

[Noobie25]

Hi all, hope someone can give me a bit of advice. I've a R reg ford escort, been having starting up problems. What happens is sometimes( espec when cold or car has not been used for a day or 2) , I turn it over engine struggles to kik in, and then I get click,click,click,click, from the stater motor, and won't turn over.
Now my first thoughts were its the battery not holding it'd charge, so off with the battery and charge with hom charger only takes about 5 minuets and wham full charge! When I put it back it, it starts no problems???

Its a unsealed battey the type where you can top up water levels, so I've topped it up a bit (wasn't dry though).So I'll see if that helps? would it help?

Anyone know what could be causing this, is it the solenoid or something?

Solenoid, starter motor or altenator?

PLease be gentle , im not very mechanicaly minded.

What kind of price am I looking at to fix?

Any help most welcome, thank in advance all.

[BroncoJoe19]

You're probably correct in suspecting the battery, or maybe the connections.
You can get the battery load tested, and see if it needs to be replaced.