The squad, comprising of eight boys from Meon Junior School, are set to play at the home of football later this month.
They defeated seven teams in two tournaments to reach the final, and the excitement at todays training session was palpable.
He told The News: ‘It’s an incredible achievement, and it took an awful lot of effort from the boys, which they put in week in and week out.
‘It just shows the passion and desire that the children have got at the school for sports and football.’
The final of the EFL Utilita Kids Cup will take place on May 21, during half-time of the League One playoff final.
Meon Junior School won the Portsmouth tournament last autumn, going on to triumph in the southern finals on March 7, in Milton Keynes.
They will be facing a side representing Sheffield Wednesday.
The training session was facilitated by Pompey in the Community.
Mr Spencer said it was ‘fantastic’ that the squad got coached by such a high calibre coach as the Pompey boss, and reckons the team will win at Wembley.
He said: ‘I think they were a bit nervous on the way down, and a bit star struck when Danny walked onto the pitch, but the experiences they are getting are ones they will cherish forever, and ones that will stick in their minds.
‘Everyone is absolutely up for it, and I’ve got to back my boys, I always do.
‘It is a once in a lifetime opportunity for them, and they’ll create memories which will live with them for the rest of their lives.’
The Fratton boss led the training session at the Portsmouth FC training ground in the glorious sunshine yesterday afternoon.
After warm ups, he conducted drills on counter-pressing out of possession, close control, shooting, and passing.
The Blues manager said he thought the personalities and ability on show were fantastic, and that ‘there was a lot to like’ about the team.
He told The News: ‘I was so impressed.
‘The standard today was great, and I thought their attitude and work rate was outstanding.
‘The quality of their play was really really good.
‘It is no surprise to me they’ve achieved what they have this season.
‘Everyone at Portsmouth Football Club is so proud of them and what they have done, and we wish them every success when they go to Wembley.’
The former PE teacher thinks the side have what it takes to succeed.
He added: ‘The opportunity to play at the home of football is something they will remember and cherish.
‘If they play like they did today, it’s going to take a very good team to beat them.
‘They’ve got a lot of enthusiasm, energy, spirit, togetherness, and these are all good qualities you find in successful teams.’
The players representing Meon Junior School include Leo Higgins and Lewis Hamza, aged 10, as well as Lorenzo Jay, Teddy Nightingale, Freddie Seabrook, Rafael Taylor-Stoakes, Anbiya Habibi, and Leon Young, all 11.