NO!!! Please don't use spastic to describe anyone at all. It's the term that used to be used to describe people with cerebral palsy but is now considered extremely offensive. There are medical terms which include the word "spastic" but they should only be used when referring to those specific terms and only ever in a medical context.
Your use of "lovely" is correct in both your examples as is your use/non-use of an article.
- For Teachers