Advice neeeded on Collie anti social behavoir towards other dogs

Bit of a long history this one.

Having had to euthanase both of the dogs that I registered with we are now down to just the one.

My previous dog history is:
Rescued (after being run over) Long haired brown Collie
Rescued (from dogs home) Short haired brown mearle BC
Rescued (from dogs home) short haired Collie (switch)
Rescured from dogs home) GSD/Lab/collie? X (milly)

We rescued Lola a 2.5yr old blue mearle from a family with other dog, un-neutered and "didnt like small dogs" from preloved who reported rescuing her from a wee soaked cat basket as a pup.

We got Lola when our last Collie had to be put down the Milly missed switch terribly, the two met in Lola's house with no problems, when we got them home they had the odd squabble over a thrown toy but nothing major.

We ended up having to wait around 12 months for Lola to go through a cycle and then have her neutered.

She's not really intrested in ball play, but will play a bit at home making excercising her difficult. She typically has 2 40+ minute walks a day.

Lola is exibiting some behaviour I'm struggling to define and hence correct.

The problem we are having when in open spaces as soon a she spots another person (without dog) and certainly other dog she starts stalking and intently staring this ends one of two ways.

If they are walking away she will trot briskly to catch them up, I keep having to call her back to heel.

If walking towards us we get her to lie down while the other dog passes, then as soon as the dog passes she bolts off.

She will then try and double back (to chase after), tail in the air.

One the occasions I've let her free run we have had mixed results.

In some instances she has chased the other dog and bitten them. In other instances (with larger dogs) does the "bossy posturing" but more confident placid dogs just ignoring and she seems to sort of want to play.

I'm struggling to determine if she is being agressive/nervous/playful.

It certainly seems that poor puppy socialisation is a contributor. In its abscence is the hurding instinct.

She seems to really not like spaniels and labs and other high energy dogs seem to get her worked up.

She is not nasty and if given a few minutes to calm down will sort of run and play with other dogs, its just getting to this point without the drama.

Having her neutered helped somewhat it calmed the behviour down (obviosuly) leading upto the cycles and during she was verging on neurotic about other people and dogs and being assertive bossy.

At the moment taking her to classes isnt an option.

Any insight would bemost helpful, thanks in advance.

With the new DDA in mind, I would not be allowing her freedom to run after other people and dogs until I had a secure recall. I would start with keeping her on a long line - or a Flexi if you need a brake to stop her. Teach her to keep her attention on you while you are walking, and keep calling her back to you using lots of yummy treats to reward a response.
Try not to let her meet other dogs head on for now, step to one side, reward her for looking and leaving, and let them pass. It is unusual that a Collie doesn't like a ball, it may come in time, but you need to find out what kind of play motivates her at the moment. Whether it is tuggy, food circuits or whatever, let her carry out these energetic activities in an enclosed area - such as garden, tennis court or a barn.
I've also had difficult dogs from shelters, and there are two books which provided me with lightbulb moments. One was Leslie McDevitt's, 'Control Unleashed', and the other was Jean Donaldson's, 'The Culture Clash'. It sounds like a socialisation issue, and I'm sure others will be along with their ideas too. I hope she gains confidence soon, and develops into a good and clever Collie.

Thanks for the response a few quick clarifications:

I have a secure recall at worst after 3 whistles, mostly on the first.

Getting her attention is a problem she is 110% focused on the other dog so will try the "look at me" training

"Try not to let her meet other dogs head on for now, step to one side, reward her for looking and leaving, and let them pass." - All ready doing this.